Spikes in light pollution data

Hi,

I thought it might be interesting to look for anomalies in the light pollution data that I posted a few days back.

So the first thing I thought might be interesting would be to look for sudden spikes in the data, and I found a few. The unit takes a sample 20 times a second and records an average of that in the log at one reading per second; though I'll need to confirm exactly how this works in particular if it averages over a longer period.

Anyway, the biggest spike showed up at about 4.34 on Dec 1st. Which from weather records and the lightmeter itself seems to have been quite a cloudy night.



These are effectively light curves, with events that appear to last about 3 seconds. So it appears that we have a sudden flash that fades over about 3 seconds. There were a smaller spike at 7.08pm earlier that night also, and 3 the previous night at 23:45, 6:39, and 6:45. There are other spikes through December but none have narrow spikes like these.

On a mostly cloudy night this is unlikely to be a meteor/fireball (unless it was very bright!). It could be lightning but I would expect to see more than spikes for the night if there was a lighting storm, and the event would be instantaneous (the sensor may be averaging over more than a second which is something I need to check). Or it could be the garda helicopter, or a glitch in the sensor.

I'll see if the sensor in TCD picked up anything, and I can ask Met Eirann if it there was lightning that night. But out of curiosity does anyone here have any weather station data or fireball camera that they could check for these times and see if there is any correlation?

Cheers,
~Al

albertw wrote:

Hi,

I thought it might be interesting to look for anomalies in the light pollution data that I posted a few days back.

So the first thing I thought might be interesting would be to look for sudden spikes in the data, and I found a few. The unit takes a sample 20 times a second and records an average of that in the log at one reading per second; though I'll need to confirm exactly how this works in particular if it averages over a longer period.

Anyway, the biggest spike showed up at about 4.34 on Dec 1st. Which from weather records and the lightmeter itself seems to have been quite a cloudy night.

These are effectively light curves, with events that appear to last about 3 seconds. So it appears that we have a sudden flash that fades over about 3 seconds. There were a smaller spike at 7.08pm earlier that night also, and 3 the previous night at 23:45, 6:39, and 6:45. There are other spikes through December but none have narrow spikes like these.

On a mostly cloudy night this is unlikely to be a meteor/fireball (unless it was very bright!). It could be lightning but I would expect to see more than spikes for the night if there was a lighting storm, and the event would be instantaneous (the sensor may be averaging over more than a second which is something I need to check). Or it could be the garda helicopter, or a glitch in the sensor.

I'll see if the sensor in TCD picked up anything, and I can ask Met Eirann if it there was lightning that night. But out of curiosity does anyone here have any weather station data or fireball camera that they could check for these times and see if there is any correlation?

Cheers,
~Al

maybe it is something simpler al. sometimes i see bloody great searchlight lighting up the clouds coming from somewhere in the city. just a suggestion.

Could it be something like a really bright iridium flare, they last only a few seconds on average.

I get these morning spikes also:



This data was recorded at 1 reading per minute.

On each of these three mornings, it happened very close to 7:30am.

Michael.

Maybe worth getting up early and having a look at, maybe you're getting some sort of red sky in the morning effect ??
or maybe a problem with the sensor, how about trying an experiment where you put the sensor in a pitch black room for an hour, and then bring it outside to daylight and see if you get the same spike.

What do the daylight sensors pick up for that time?